JP5258585B2 - Newspaper for offset printing - Google Patents

Description

The present invention relates to newsprint for offset printing. Recently, in order to improve operability at the time of papermaking, or to increase the papermaking pH due to neutralization and to reduce soiling in the papermaking system when calcium carbonate is internally added as a filler, the amount of internal sizing agent is reduced. Or paper is made without addition, and the sizing degree is often improved by applying a surface sizing agent.
The present invention relates to newsprint paper that is produced while suppressing the use of such an internally added sizing agent, and relates to newsprint paper for offset printing used in a cold set type offset printing press.

In recent years, color printing and speeding-up of printing have been rapidly progressing, and newsprint paper suitable for color printing, that is, newsprint paper for offset printing with better printability and printing workability has come to be demanded.
On the other hand, in color printing, since a plurality of colors are applied in a plurality of times, color misregistration occurs depending on the state of newsprint paper for offset printing (hereinafter simply referred to as newsprint paper) supplied to the rotary press. there is a possibility.

Hereinafter, the color misregistration that occurs during color printing of a newspaper printing press will be described.
First, in a newspaper printing rotary press, printing is performed while applying dampening water to newsprint paper supplied to the rotary press. When dampening water is applied, newspaper paper expands, so the printing section of the rotary press corrects such expansion, and the position of the image line portion where the first color is printed matches the position of the image line portions after the second color. The print position is adjusted so that
Here, in a newspaper printing rotary press, printing is continuously performed on a sheet of newsprint, and it is necessary to supply the newsprint rolled up in a plurality of rolls to the rotary press while sequentially connecting them. .
However, the newsprints wound around each roll do not necessarily have the same physical properties, so when newsprints with different physical properties are connected, the newsprint paper stretches when dampening water is applied before and after the joints. There is a difference in quantity.
Then, the printing section of the rotary press adjusts the printing position according to the physical properties of the newsprint before the paper splicing, so when it changes to a new newsprint, the image line section on which the first color is printed and the second and subsequent colors are printed. Misregistration (positional deviation) occurs in the image area. This misregistration is color misregistration.

Such color misregistration is corrected by a register adjusting device provided in the rotary press. However, it takes a certain amount of time until the correction by the register adjusting device is completed after the color misregistration occurs. For this reason, what is printed between the occurrence of color misregistration and the completion of correction is discharged as a defective product. The more copies that are discharged, the worse the printing efficiency.
In particular, newspaper paper has a low basis weight of 40 to 43 g / m ² in addition to performing high-speed and large-volume printing such as 200,000 copies per hour compared to other printing paper (for example, coated printing paper). Therefore, since the individual difference in elongation when fountain solution is applied increases, special consideration is required for color shift.

  As described above, the color shift is affected by the amount of water absorbed by the newsprint when dampening water is applied. Therefore, in order to prevent such color shift, the degree of size and moisture absorption resistance are improved. Focusing attention, the following technologies have been proposed.

(1) In Patent Document 1, a coating layer mainly composed of a pigment and an adhesive is provided on at least one side of a base paper, and the maximum signal intensity is 0.1 to 1.0 seconds or less as measured by the EST12 surface / size tester. A technique adjusted to be disclosed is disclosed.

  However, the technique of Patent Document 1 merely specifies conditions necessary for newsprint in order not to cause color misregistration, and a method for improving the size of newsprint required to prevent color misregistration and moisture absorption. It does not suggest a way to improve resistance.

  The following techniques have been proposed as techniques for improving the sizing degree and moisture absorption resistance and preventing the occurrence of color misregistration by adjusting the surface treatment agent.

(2) Patent Document 2 discloses a technique in which a surface sizing agent containing a styrenic monomer is used as a surface treating agent and adjusted to have a specific sizing characteristic. .
(3) Patent Document 3 employs a surface treatment agent containing two components of a styrene sizing agent composed of cationic starch and a water-soluble copolymer synthesized from a styrene monomer and an anionic monomer. Have been disclosed.
(4) Patent Document 4 discloses a technique in which a water-soluble surface sizing agent that is a copolymer containing a styrene monomer and a cationic vinyl monomer is employed as the surface sizing agent.
(5) Patent Document 5 was synthesized from a monomer containing at least a (meth) acrylic acid ester having 1 to 18 carbon atoms and an ethylenically unsaturated carboxylic acid as a surface treatment agent. A technique that employs a copolymer as a main component and defines the characteristics of the contact angle between the surface treatment agent and water is disclosed.

  As described above, Patent Documents 2 to 5 disclose a technique for improving surface sizing properties and water absorption resistance by using a surface treatment agent, but high sizing degree and high water absorption necessary for improving color misregistration are disclosed. It is difficult to get resistance.

  On the other hand, it is not intended to prevent color misregistration, but as a method to improve the sizing degree and moisture absorption resistance, it uses a ketene dimer sizing agent that has a small size and high size effect as a surface treatment agent. Has also been developed.

(6) In Patent Document 6, after adding a ketene dimer sizing agent and a paper surface finishing agent to neutral newsprint paper with a gate roll coater, the paper is passed through a soft calender having a surface temperature of 50 ° C. or more. A technique for expressing the size degree is disclosed.
(7) Patent Document 7 discloses a technique in which a coating layer containing a modified starch, an alkyl ketene dimer, and an anti-slip agent is provided on the surface of the base paper, and the dynamic friction coefficient of the surface is in the range of 0.40 to 0.70. .
(8) Patent Document 8 discloses a surface sizing composition containing a ketene dimer system sizing agent and a water-soluble polymer compound in a specific range of mass ratio.

  However, while the ketene dimer sizing agent has a high size effect, slippage increases on the surface of the coated newsprint, so that wrinkles and paper breaks may occur due to paper flow caused by this slippage.

Patent Document 6 does not specify any components of the paper surface finishing agent to be applied together with the ketene dimer sizing agent and can improve the sizing property. The problem of slipping will remain.
Further, Patent Document 7 solves the problem of surface slippage during printing by using an anti-slip agent together with an alkyl ketene dimer. However, the coating amount of the two components of the modified starch and the alkyl ketene dimer is 0.5 to 2.0 g / m ² , and the blending ratio thereof is 0.5 to 3.0 parts of the alkyl ketene dimer with respect to 10 parts of the modified starch. The coating amount of the alkyl ketene dimer is as high as 0.024 to 0.46 g / m ^2, and there is a concern about the problem of contamination of the coating apparatus.

  On the other hand, in Patent Document 8, since the surface sizing composition contains the ketene dimer system sizing agent and the water-soluble polymer compound in a mass ratio within a specific range, it is possible to reduce the contamination of the papermaking apparatus. There is a description. However, the technique of Patent Document 8 is applied to paper that does not require surface paper strength imparted by oxidized starch or the like, and is adapted to paper that does not require high surface paper strength or paper with a high kraft pulp content. However, it is not applicable to newsprint that requires high surface paper strength and a high blending ratio of waste paper pulp.

As described above, according to the above-described conventional technology, it is possible to prevent color misregistration that occurs during color printing of a newspaper printing press, and to cause other problems (such as coating device contamination) as a side effect of preventing such color misregistration. It cannot be prevented.
And the conditions which can prevent the color misregistration which generate | occur | produces at the time of color printing of a newspaper printing press cannot be grasped | ascertained now.

JP 2005-187949 A JP 2007-146333 A JP-A-2005-76146 WO2005 / 003457 Publication JP 2003-253598 A Japanese Patent Laid-Open No. 9-111161 Japanese Patent Laid-Open No. 7-279094 JP-A-7-109695

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a newsprint for offset printing that has sufficient size characteristics and does not cause color misregistration even when multicolor printing is performed.

The newsprint for offset printing according to the first invention has a surface treatment agent coated on both sides of the base paper so that the water tension is 3.5 seconds or more. The surface treatment agent comprises an adhesive, an alkyl ketene dimer system a surface sizing agent, contains a polymer-based surface sizing agent, the coating amount of the alkylketene dimer based surface sizing agent is a per side 0.001~0.02g / m ^2, the alkyl ketene dimer based surface size The ratio of the coating amount of the adhesive and the polymeric surface sizing agent is 1 to 4 to 1 and the adhesive contains a polyacrylamide adhesive and a starch adhesive, The mass ratio of the polyacrylamide adhesive in the agent is 5% by mass or more .
In this specification, “waterproof tension” means a piece of paper made of newsprint paper for offset printing having a length of 15 mm in the CD direction and a length of 250 mm in the MD direction with respect to a constant-speed stretch type tensile tester. The paper piece is held so that both ends in the MD direction are held and the distance between the members holding the paper piece is 180 mm, and the paper piece is stretched along the MD direction by a constant speed extension type tensile tester and applied to the paper piece. When the tensile load is 6.0 N, when the paper piece stops stretching and 15 μl of water is attached to the center of the paper piece, the tensile force applied from the paper piece to the constant-speed extension type tensile tester after the water is attached The time required for the load to drop from 6.0N to 4.0N.
Offset printing newsprint second invention is the first invention, the coating amount of the adhesive, characterized in that it is a single-sided per 0.3g~1.0g / m ^2.
The newsprint for offset printing according to the third invention is characterized in that, in the first or second invention, a mass ratio of the polyacrylamide adhesive in the adhesive is 5 to 10 mass% .
The newsprint for offset printing according to the fourth aspect of the present invention is the first, second or third aspect of the invention . In the test method based on 32-2, the time for absorbing 5 μl of dripped water is 30 seconds or more.

According to the first to third inventions, since the water-resistant tension representing sizing properties and tensile properties is high, color misregistration during printing can be prevented. In addition, since the surface treatment agent includes both an alkyl ketene dimer surface sizing agent and a polymer surface sizing agent, the alkyl ketene dimer surface sizing agent has a high sizing effect by the alkyl ketene dimer surface sizing agent. The amount can be reduced. As a result, it is possible to prevent slippage during printing, wrinkling due to paper flow, paper breakage, and the like, which are problems when an alkyl ketene dimer surface sizing agent is used for newsprint. In addition, since the surface treatment agent also includes an adhesive, it is possible to suppress the occurrence of piling during printing while maintaining the size effect of the surface sizing agent. Furthermore, a degree of sizing that does not cause color misregistration can be imparted, and troubles such as contamination can be prevented from occurring in the coating apparatus. Furthermore, by using a suitable combination of a starch adhesive with a low molecular weight and good dispersibility on the paper surface and a polyacrylamide adhesive with a high covering ability at the site where the molecular weight is adhered, Penetration into the paper layer can be prevented. Then, since the surface treatment agent tends to stay on the paper surface, the size effect of the surface sizing agent can be further increased, and in addition, the water tension can be increased.
According to the fourth aspect of the invention , since the water absorption resistance is large, it is possible to suppress the elongation due to water absorption at the time of printing, and thus it is possible to prevent color misregistration at the time of printing.

It is the figure which showed the coating conditions of the surface treatment agent of the newsprint for offset printing of Examples 1-8 and Comparative Examples 1-5, and the evaluation result of the water resistance tension, the water absorption time, the stain | pollution | contamination of a coating apparatus, and color shift. is there.

  The newsprint for offset printing of the present invention is adjusted to have properties suitable for multi-color printing by a rotary press, and the water tension measured under conditions close to actual printing becomes a predetermined value. It is characterized by having been adjusted in this way.

Specifically, the newsprint for offset printing of the present invention is adjusted so that the value of the waterproof tension measured by the method described later becomes a predetermined value. The water-resistant tension measured by the method described later properly represents the size and tensile properties of newsprint during multicolor printing on a rotary press.If this value is high, color misregistration during printing will occur. Can be prevented.
With the predetermined value mentioned above, the value of the waterproof tension measured by the method described later is 3.5 seconds or more, preferably 3.5 to 10 seconds. This is because when the water resistance tension is less than 3.5 seconds, the occurrence of color misregistration increases, and when the water resistance tension is greater than 10 seconds, no color misregistration occurs, but the effect of suppressing color misregistration reaches its peak. .

(Measurement method of water tension)
As described above, in the present invention, the water resistant tension is adopted for specifying the properties of the newsprint, but a method for measuring the water resistant tension will be described below.
In the following, the case of using the constant speed extension type tensile tester specified in JIS P8113 (2006) is described for measuring the water-resistant tension, but the machine used for measuring the water-resistant tension is not particularly limited. Anything that can be operated as described below may be used.

For the measurement of the water resistance tension, a piece of paper having a lateral direction (CD direction) of 15 mm and a longitudinal direction (MD direction) of 250 mm is used. The MD direction is a direction parallel to the paper traveling direction on the paper machine, and the CD direction is a direction orthogonal to the MD direction.
First, both ends of this paper piece in the MD direction are held by clips of a constant speed extension type tensile tester. At this time, it is held so that the distance between the clips holding the paper piece is 180 mm.
Next, the clip of the constant speed extension type tensile tester is moved to stretch and stretch the paper piece along its MD direction. Then, the movement of the clip is stopped when the tensile load applied to the paper piece becomes 6.0N. In other words, the clip position is fixed so that a tensile force of 6.0 N is applied to the clip from the piece of paper. The tensile load of 6.0 N applied to the paper piece is a load that is approximately the same as the tension applied to the newsprint in the offset printing press.

  When the position of the clip is fixed, 15 μl of water is attached to the center of the paper piece. When water is attached, the paper piece absorbs water, and when water is absorbed, the paper piece becomes easy to stretch. Then, since the tensile force applied to the clip from the paper piece is reduced, the time required for the tensile force to drop to 4.0 N after the water is attached to the paper piece is measured, and this time is taken as the water resistant tension.

Conventionally, as a method for evaluating color misregistration, a method for measuring tensile strength, elongation, etc. related to water absorption (water droplet absorption time), contact angle of water droplets, or tensile properties related to size characteristics has been adopted. However, these were methods for separately measuring sizing and tensile properties.
In addition, the wet tensile strength test method of JIS P8135 (1998) measures the strength of paper usually immersed in water for 1 hour, and it can be said that the size and tensile properties are measured simultaneously. However, since the amount of dampening water that adheres to the paper in the actual printing process is less than the amount of water that adheres to the paper in this test, this test was also less accurate as an evaluation method for color misregistration. .

In the color printing section of a newspaper printing press, the time required for the paper to pass through the first roll after passing through the first roll is a short time, and therefore, due to a large tensile load that causes the dry paper to break. In the evaluation or the evaluation in a state where the paper is immersed in water for a long time and the tension of the paper is lowered, the color shift occurring at the time of actual printing on the rotary press cannot be evaluated.
In order to evaluate the color misregistration that occurs during actual printing, the degree of water penetration in a short time and the tensile properties of the paper immediately after water penetration should be evaluated simultaneously. That is, the slight elongation of the paper caused by the tension during offset printing should be evaluated.

  The measuring method of the water-resistant tension adopted in the present invention can simultaneously measure the size and tensile properties, and reflects the above-mentioned properties of newsprint paper under conditions closer to actual printing. Therefore, for newsprint paper, color misregistration when color printing on a newspaper printing press is performed can be appropriately evaluated, and the properties of newsprint paper that can prevent color misregistration can be specified.

The constant-speed extension type tensile tester is preferably an apparatus that can be programmed so that extension stops when the tensile load reaches 6.0N.
Moreover, there is no restriction | limiting in the method of attaching water to a paper piece, The method of dripping water with a spoid or a pipette, the method of attaching water with the brush (brush) which gave a fixed amount of water, the method by roll transfer, etc. are mentioned. . In the present invention, the amount of water adhering to the piece of paper is 15 μl. However, the amount of water does not have to be exactly 15 μl, and even if there is a slight error, the value of the resistance to water tension is not affected.

(Water absorption time)
Further, the newsprint for offset printing according to the present invention satisfies the above-mentioned conditions of the water-resistant tension and has a JAPAN TAPPI No. In the test based on 32-2, the water absorption time (amount of dripped water 5 μl) is 30 seconds or more, preferably 30 to 200 seconds. This is because when the water absorption time is lower than 30 seconds, the progress of the decrease in the tension of the paper piece is accelerated, so that the water-resistant tension is insufficient. .

(Newspaper paper that satisfies the above water tension)
The newsprint of the present invention can be adjusted for water resistance tension as described above by the following method. For example, adjusting jet wire ratio (raw material jet speed / paper machine wire speed ratio), increasing the distribution of softwood kraft pulp, promoting pulp beating, adding internal sizing agent to pulp, wet paper strength enhancer as pulp The water tension of the newsprint can be adjusted by methods such as adding to the base, increasing the basis weight of the base paper, and suppressing the amount of filler added.
However, instead of the water tension adjustment method described above or together with the water tension adjustment method described above, the water tension can be adjusted by adjusting the components and coating amount of the surface treatment agent applied to the base paper described below. Thus, it is possible to achieve the above-described water-resistant tension more effectively and reliably.

(Base paper)
First, before explaining the surface treating agent and the like used in the newsprint of the present invention, the base paper of the newsprint of the present invention will be briefly explained.
The base paper is mainly made from waste paper deinked pulp (DIP) and also contains mechanical pulp. Waste paper deinked pulp is obtained by deinking waste newspaper, magazine waste paper, and the like, and is preferably blended in a high amount from the viewpoint of resource reuse. Thermomechanical pulp (TMP), groundwood pulp (GP), refiner groundwood pulp (RGP), pressured groundwood pulp (PGW), etc. can be used as the mechanical pulp. Since these mechanical pulps contribute to improving the opacity of newsprint, an appropriate amount is mixed.
In addition, chemical pulp such as softwood kraft pulp (NKP) and hardwood kraft pulp (LKP) can be appropriately blended with the pulp used as the raw material of the base paper, such as waste paper deinked pulp and mechanical pulp. Such chemical pulp contributes to improving the strength of newsprint.

In the newsprint of the present invention, after mixing pulp as a raw material in the preparation step, a filler can be added (internally added) to the pulp in order to improve the properties of the base paper.
For example, when a filler is added for the purpose of improving opacity, white carbon, kaolin, talc, calcium carbonate, or the like is added.
Also, saponifying rosin sizing agent, rosin emulsion sizing agent, alkyl ketene dimer, alkenyl succinic anhydride and other sizing agents, and fixing agents such as sulfuric acid band, cationic starch and cationic polyacrylamide resin are added as necessary. be able to.
In addition, additives such as a dry paper strength enhancer, a wet paper strength enhancer, a slime control agent, a pitch control agent, an antifoaming agent, and a dye can be internally added as necessary.

(Surface treatment agent)
The newsprint of the present invention is adjusted so that desired sizing properties and water tension can be obtained by applying a surface treatment agent to the surface of the base paper as described above.
Below, the surface sizing agent and adhesive contained in the surface treatment agent, and the coating amount thereof will be described.
The surface treatment agent includes substances other than the surface sizing agent and adhesive described later, for example, known chemicals such as pigments, anti-slip agents, lubricants, thickeners, antifoaming agents, and dyes. These substances can be mixed as appropriate in order to obtain properties other than the size and water tension required for newsprint for offset printing, such as whiteness, opacity, and friction coefficient.

(Surface sizing agent)
The surface treatment agent used in the newsprint of the present invention uses a surface sizing agent containing an alkyl ketene dimer surface sizing agent and a polymer surface sizing agent. Two surface sizing agents are used for the following reason.
When an alkyl ketene dimer surface sizing agent is used for newsprint, a high sizing effect can be obtained. However, if the amount added is large, slippage during printing, wrinkling due to paper flow, paper breakage, etc. may occur. Becomes higher.
However, if a polymer surface sizing agent is used together with an alkyl ketene dimer surface sizing agent, the amount of the alkyl ketene dimer surface sizing agent can be suppressed, and an anti-slip effect by the polymer surface sizing agent can be obtained. Therefore, the above problem can be prevented from occurring. That is, by using the two surface sizing agents as described above, it is possible to prevent slipping during printing, wrinkling due to paper flow, paper breakage, etc. while obtaining a high size effect.

(Alkyl ketene dimer surface sizing agent)
Next, the alkyl ketene dimer surface sizing agent used in the present invention will be described in detail.
As the alkyl ketene dimer type surface sizing agent used in the present invention, the following general formula [Chemical Formula 1]
[Formula 1]:
R1-CH = CO
｜ ｜
R2-HC-C = O
(Wherein R1 and R2 are a saturated or unsaturated hydrocarbon group having 8 to 30 carbon atoms)
An alkyl ketene dimer (AKD) represented by: AKD is used after being dispersed in water by an emulsifier. In which R1
, R2 represent the same or different hydrocarbon groups. Examples of the hydrocarbon group include alkyl groups such as decyl, dodecyl, tetradecyl, hexadecyl, octadecyl and eicodecyl, alkenyl groups such as tetradecenyl, hexadecenyl and octadecenyl, alkyl-substituted phenyl groups such as octylphenyl and nonylphenyl, nonylcyclohexyl and the like. An alkyl-substituted cycloalkyl group, an aralkyl group such as phenylethyl, and the like. These ketene dimer compounds can be used alone or in combination of two or more.

The ketene dimer compound preferably has a melting point of 40 ° C. or lower. Here, the melting point means an ascending melting point and is a value measured by a capillary method. The reason why the melting point is preferably 40 ° C. or lower is as follows.
The surface sizing agent used for the surface sizing is required to have stability against heat and mechanical impact, but a general ketene dimer compound is a mixture of straight-chain saturated fatty acids having 16 and 18 carbon atoms from beef tallow. The one manufactured from is used.
In the case of surface sizing, a surface treatment agent is applied to the paper surface after the paper layer is formed, gate roll coater, 2 roll size press, rod metal ring size press, blade metal ring size press, blade coater, rod coater, bar coater. Apply using etc. The purpose of this surface sizing may include imparting surface strength or printability to the paper in addition to imparting size to the paper. In order to impart these functions, starch-based adhesives such as oxidized starch and phosphate esterified starch, and water-soluble polymers such as carboxymethyl cellulose and polyvinyl alcohol are used. Must be used after being gelatinized. When these water-soluble polymer substances and the surface sizing agent are used in combination, the aqueous solutions of both are mixed and used. At this time, the water-soluble polymer substance is in a high temperature state due to the cooking treatment, and the surface sizing agent also becomes high temperature due to the mixing of the two aqueous solutions. The temperature at this time is usually 40 to 60 ° C., and the surface sizing agent is required to have thermal stability that can withstand a wide temperature range.
Since the sizing composition for papermaking containing a ketene dimer compound having a melting point of 40 ° C. or less has excellent heat and mechanical stability over the temperature range in which the coating liquid is used, the occurrence of wrinkles is extremely high. Therefore, the coating apparatus can be less contaminated and the operability can be improved.

  The alkyl ketene dimer surface sizing agent having a melting point of 40 ° C. or lower can be produced by a conventionally known method. For example, a ketene dimer compound and a protective colloid and / or a dispersant are mixed in an aqueous solvent at a temperature equal to or higher than the melting point of the ketene dimer compound represented by the general formula [Chemical Formula 1], and a homomixer, a high pressure discharge type homogenizer is mixed. It can be obtained by uniformly dispersing with various known emulsifiers such as an ultrasonic emulsifier. Further, known protective colloids and / or dispersants can be used. For example, a cationic dispersant such as cationized starch, an anionic dispersant such as naphthalene sulfonate-formaldehyde condensate, lignin sulfonate, a nonionic dispersant such as sorbitan ester, or a cationic, anionic or amphoteric Examples include polymer protective colloids such as acrylamide polymers.

  Further, the ketene dimer compound added to the surface treatment agent preferably has a concentration of 10 to 30% by mass and a dispersed phase particle size of 10 μm or less. The reason is that the dispersion is stable and the effect of size is improved.

(Polymer surface sizing agent)
Examples of the polymeric surface sizing agent used in the present invention include anionic polymer compounds such as styrene maleic acid copolymers, styrene acrylic acid copolymers, and olefin maleic acid copolymers, and styrene polymers. There is a cationic polymer compound, but there is no particular limitation as long as it has a property that the size effect is high and the viscosity is appropriate.

(Blend ratio of surface sizing agent)
Here, when applied to the base paper, the coating amount of the alkyl ketene dimer surface sizing agent is 0.001 to 0.02 g / m ² on one side, and the alkyl ketene dimer surface sizing agent and the polymer surface sizing agent The coating amount ratio is preferably 1 to 4 to 4 to 1.

If the coating amount of the alkyl ketene dimer surface sizing agent is less than 0.001 g / m ² on one side, the sizing degree will be insufficient, and if it exceeds 0.02 g / m ² , troubles such as newsprint slippage and smearing of the coating device are likely to occur. Because it becomes.
Further, even when the coating amount is the above, when the ratio of the coating amount of the alkyl ketene dimer surface sizing agent to the polymer surface sizing agent exceeds 1: 4 and the amount of the polymer surface sizing agent increases, the alkyl ketene dimer increases. Since the ratio of the system surface sizing agent becomes small, the sizing degree is insufficient. On the other hand, when the alkyl ketene dimer surface sizing agent is increased beyond 4 to 1, a problem of contamination of the coating apparatus tends to occur.
Therefore, in order to give the newspaper paper a degree of sizing that does not cause color misregistration during printing, and to prevent the coating apparatus from causing troubles such as dirt, it is necessary to apply alkyl ketene dimer surface sizing agent. The surface treatment agent is adjusted so that the amount is 0.001 to 0.02 g / m ^{2 on} one side and the ratio of the coating amount of the alkyl ketene dimer surface sizing agent to the polymer surface sizing agent is 1 to 4 to 4 to 1. It is preferable to adjust and apply.

(adhesive)
Since the surface treatment agent also contains an adhesive, it is possible to suppress the occurrence of piling during printing while maintaining the size effect of the surface sizing agent.
The adhesive used is not particularly limited, but preferably contains a polyacrylamide (PAM) adhesive and a starch adhesive. In this case, by using a starch adhesive with a low molecular weight and good dispersibility on the paper surface, and a polyacrylamide adhesive with a high covering ability at the site where the molecular weight is adhered, the surface treatment agent is applied to the paper layer. Can be prevented. Then, since the surface treatment agent tends to stay on the paper surface, the size effect of the surface sizing agent can be increased, and the water tension can be increased, so that the occurrence of color misregistration can be suppressed.

Examples of the polyacrylamide adhesive include nonionic polyacrylamide, cationic polyacrylamide (for example, water-soluble polyacrylamide having a tertiary amine group and / or a quaternary ammonium base), an anionic polyacrylamide, or an amphoteric polyacrylamide. Etc. can be used.
As the starch-based adhesive, oxidized starch, enzyme-modified starch, thermochemically-modified starch, phosphate esterified starch, hydroxyethylated starch and the like can be used.

  In addition to polyacrylamide adhesives and starch adhesives, cellulose compounds such as carboxymethyl cellulose and hydroxyethyl cellulose, proteins such as casein, synthetic protein, soybean protein, and synthetic polyvinyl alcohol are also used. Alternatively, an adhesive such as a synthetic latex such as a styrene-butadiene copolymer, a methyl methacrylate-butadiene copolymer, or an acrylonitrile-butadiene copolymer may be used.

(Amount of adhesive applied)
The coating amount of the adhesive applied to the newsprint of the present invention is preferably 0.3 g / m ² or more and 1.0 g / m ² or less in terms of solid content per side.
If the coating amount of the adhesive is less than 0.3 g / m ² per side, it is difficult to uniformly apply the surface treatment agent to the paper surface, and uneven coating tends to occur, while the coating amount is 1.0 g per side. This is because if it exceeds / m ² , ink drying defects and Nepari troubles are likely to occur.

In the present invention, as a coater for applying a surface treatment agent to a base paper, a gate roll coater, a 2-roll size press, a rod metering size press, a blade metering size press, a blade coater, a rod coater, a bar coater, etc. A gate roll coater suitable for coating with a low coating amount is preferable.
In addition, the paper coated with the surface treatment agent is subjected to a calendar process through a drying process, but the calendar apparatus for performing the calendar process is composed of a machine calendar whose both surfaces are treated with a metal roll, an elastic roll and a metal roll. Soft calendars, shoe calendars, etc. can be used.

  Next, with respect to the newsprint of the present invention (Example) and the newsprint of the comparative example, the paper quality (waterproof tension, water absorption time), the presence or absence of contamination of the coating apparatus and the occurrence of color misregistration are compared, and the effect of the present invention It was confirmed. In the following, unless otherwise specified, the mass%, mass part, and coating amount are represented by solid content or active ingredients.

Example 1
The newsprint of Example 1 is newsprint with a basis weight of 43.0 g / m ² , and is manufactured by applying a surface treatment agent to the base paper, and then drying and calendering. The base paper of the newsprint, the surface treatment agent, and the coating amount of the surface treatment agent of Example 1 are as follows.
1) Base paper The yield of base paper is based on 100 parts by weight of pulp raw material in which 80% by mass of DIP (Canadian standard freeness 180ml) and 20% by mass of TMP (Canadian standard freeness 110ml) are mixed as pulp raw materials. 0.02 parts by mass of an improver (product name: ND260 / manufactured by Hymo Co., Ltd.) and 5 parts by mass of kaolin were added, and paper making was performed with a hybrid former type paper machine.
2) Surface treatment agent The following were used for the surface sizing agent and the adhesive of the surface treatment agent.
(1) Surface sizing agent As the surface sizing agent, alkyl ketene dimer surface sizing agent (product name: SE2395 / manufactured by Seiko PMC Co., Ltd.), polymer surface sizing agent (olefin surface sizing agent, product name: Polymaron OM) -25 / Arakawa Chemical Industries, Ltd.) was used.
(2) Adhesive Oxidized starch (product name: MS9000 / manufactured by Nippon Shokuhin Kako Co., Ltd.) and polyacrylamide adhesive (product name: Polymer Set HP-710 / manufactured by Arakawa Chemical Industries, Ltd.) are solid for the adhesive. A 9: 1 mix was used.
3) Coating amount As for the surface treatment agent including the surface sizing agent and adhesive as described above, the coating amount per one side of the adhesive is 0.4 g / m ² and the coating amount per one side of the alkyl ketene dimer surface sizing agent is applied. amount 0.015 g / m ^2, as the coating amount per one surface of the polymer based surface sizing agent is 0.015 g / m ^2, it was coated with the base paper both surfaces the same coating amount at the gate roll coater.

(Example 2)
The newsprint of Example 2 is different from the newsprint of Example 1 only in the coating amount of the surface sizing agent, and the coating amount per side of the alkyl ketene dimer surface sizing agent is 0.001 g / m ² , Coating was performed so that the coating amount per one side of the polymer surface sizing agent was 0.004 g / m ² .

(Example 3)
The newsprint of Example 3 differs from the newsprint of Example 1 only in the coating amount of the surface sizing agent, and the coating amount per side of the alkyl ketene dimer surface sizing agent is 0.02 g / m ² , Coating was performed so that the coating amount per one side of the polymer surface sizing agent was 0.005 g / m ² .

Example 4
The newsprint of Example 4 is different from the newsprint of Example 1 only in the coating amount of the surface sizing agent, and the coating amount per side of the alkyl ketene dimer surface sizing agent is 0.02 g / m ² , Coating was performed so that the coating amount per one side of the polymer surface sizing agent was 0.02 g / m ² .

(Example 5)
The newsprint of Example 5 is different from the newsprint of Example 1 in the amount of polymer surface sizing agent used and the coating amount of the surface sizing agent. Agent (product name: Polymaron NS-25 / Arakawa Chemical Industries, Ltd.), the coating amount per side of the alkyl ketene dimer surface sizing agent is 0.001 g / m ² , one side of the polymer surface sizing agent Coating was performed so that the coating amount per unit was 0.001 g / m ² .

(Example 6)
The newsprint of Example 6 differs from the newsprint of Example 5 in the amount of coating of the used adhesive and the adhesive and surface sizing agent. For the adhesive, oxidized starch (product name: MS9000 / manufactured by Nippon Shokuhin Kako Co., Ltd.) and polyacrylamide type adhesive (product name: Polymer Set HP-710 / manufactured by Arakawa Chemical Co., Ltd.) in a solid content of 19: 1. The mixture was used. The coating amount per side of the adhesive is 0.8 g / m ² , the coating amount per side of the alkyl ketene dimer surface sizing agent is 0.01 g / m ² , and the coating amount per side of the polymer surface sizing agent is Coating was performed so that the work amount was 0.005 g / m ² .

(Example 7)
The newspaper of Example 7 is different from the newspaper of Example 1 only in the material of the base paper.
The base paper of the newsprint of Example 7 is 50% by mass of DIP (Canadian standard freeness 180 ml), 30% by mass of TMP (Canadian standard freeness 110 ml), and softwood bleached kraft pulp (Canadian standard drainage). The yield improver (product name: ND260 / manufactured by Hymo Co., Ltd.) 0.02 parts by mass, polyamide epichlorohydrin-based wet paper strength enhancer (Product name: WS4024 / Seiko PMC Co., Ltd.) 0.2 parts by mass, Neutral rosin emulsion sizing agent (Product name: CC1404 / Seiko PMC Co., Ltd.) 0.2 parts by mass, Sulfuric acid band 0.8 parts by mass, Kaolin 5 parts by mass Part was added and paper was made with a hybrid former type paper machine.

(Example 8)
The newsprint of Example 8 is different from the newsprint of Example 7 in that the coating amount of the adhesive and the surface sizing agent is different, the coating amount per side of the adhesive is 0.8 g / m ² , and the alkyl ketene. Coating was performed so that the coating amount per side of the dimer surface sizing agent was 0.02 g / m ² and the coating amount per side of the polymer surface sizing agent was 0.08 g / m ² .

(Comparative Example 1)
The newsprint paper of Comparative Example 1 is different from the newsprint paper of Example 1 in the surface sizing agent and the coating amount thereof, and does not use an alkyl ketene dimer surface sizing agent as the surface sizing agent, but the polymer surface size. Only the agent is used. And it applied so that the coating amount per one side of a surface sizing agent might be 0.03 g / m < ² >.

(Comparative Example 2)
The newsprint of Comparative Example 2 is different from the newsprint of Example 1 in the surface sizing agent and its coating amount, and only the alkyl ketene dimer surface sizing agent is used as the surface sizing agent, and coating per side is performed. The coating was performed so that the amount was 0.025 g / m ² .

(Comparative Example 3)
The newsprint of Comparative Example 3 differs from the newsprint of Example 1 only in the amount of surface sizing agent applied, and the coating amount per side of the alkyl ketene dimer surface sizing agent is 0.0008 g / m ² , Coating was performed so that the coating amount per one side of the polymer surface sizing agent was 0.004 g / m ² .

(Comparative Example 4)
The newspaper of Comparative Example 4 differs from the newspaper of Example 1 only in the coating amount of the surface sizing agent, and the coating amount per side of the alkyl ketene dimer surface sizing agent is 0.025 g / m ² , Coating was performed so that the coating amount per one side of the polymer surface sizing agent was 0.005 g / m ² .

(Comparative Example 5)
The newsprint of Comparative Example 5 is different from the newsprint of Example 5 in that the adhesive and its coating amount are different from each other, using only oxidized starch without using a polyacrylamide adhesive as the adhesive. The coating was performed so that the coating amount per side was 0.4 g / m ² .

The evaluation method for newsprint for offset printing was as follows.
(Water resistance)
JISP8113 (2006) paper and paperboard-Test method for tensile properties-Part 2: Based on the constant-speed stretching method, a piece of paper in the transverse direction (CD direction) 15 mm and the longitudinal direction (MD direction) 250 mm Clamp the clip of a tensile tester (Autograph AG-I 500N / manufactured by Shimadzu Corporation) at an interval of 180 mm and start stretching. When the tensile load reaches 6.0 N, the stretching is stopped and the paper is placed at the center of the piece of paper. 15 μl of water was attached with a brush, and the time required for the tensile load to decrease from 6.0 N to 4.0 N was measured. The tensile load is a load per 15 mm width of the paper piece. The same measurement was repeated 5 times, and the average value was calculated. Note that the samples were prepared in advance according to JIS P8111 (1998) at 23 ° C. ± 1 ° C. and (50 ± 2)% r. h. What was conditioned for 24 hours in the standard state was measured in the standard state.

(Water absorption time)
JAPAN TAPPI No. Based on 32-2, the measurement was performed with an amount of dripped water of 5 μl.

(Color shift)
Four-color printing was performed in the order of ink, indigo red and yellow at a printing speed of 120,000 copies / hour on both sides. Paper splicing from the old winding to the new winding was carried out leaving a winding length of 20 m, and the amount of yellow misalignment with respect to the black ink immediately after discharging 50 copies was measured. The paper splicing was performed 10 times, the average value of the shift amounts was calculated, and the color shift was evaluated according to the following criteria.
A: Deviation is less than 0.1 mm,
○: Deviation amount is 0.1 mm or more and less than 0.5 mm,
×: Deviation amount is 0.5mm or more

(Experimental result)
FIG. 1 shows the coating conditions of the surface treatment agent for newspapers for offset printing in Examples 1 to 8 and Comparative Examples 1 to 5, and the evaluation results of water resistance tension, water absorption time, stains and color shift of the coating apparatus. .

  In the newsprint for offset printing shown in Examples 1 to 8, the water resistance tension is 3.5 seconds or more, the water absorption time is 30 seconds or more, the evaluation of color misregistration is good, and the coating apparatus is stained. Absent.

  On the other hand, in Comparative Example 1, an alkyl ketene dimer surface sizing agent was not used as a surface sizing agent, but only an olefin surface sizing agent was used. The water absorption time was low and the water resistance tension was as low as 3.4 seconds. Color shift evaluation is getting worse.

Comparative Example 2 is an example in which only an alkyl ketene dimer type surface sizing agent was used as the surface sizing agent. The coating amount of the surface sizing agent was as large as 0.025 g / m ^2, and the coating apparatus was soiled. It was difficult to continuously produce paper.

Comparative Example 3 uses an alkyl ketene dimer surface sizing agent and a polymer surface sizing agent as the surface sizing agent, but the coating amount of the alkyl ketene dimer surface sizing agent is as small as 0.0008 g / m ² , Moreover, since the ratio of the coating amount of the alkyl ketene dimer surface sizing agent to the polymer surface sizing agent is 1: 5, the water absorption time is insufficient, and the water resistance tension is as low as 3.2 seconds. It has become.

In Comparative Example 4, the alkyl ketene dimer surface sizing agent and the polymer surface sizing agent are used in combination, but the ratio of the coating amount of the alkyl ketene dimer surface sizing agent to the polymer surface sizing agent is 5: 1. There are many alkyl ketene dimer surface sizing agents, and the coating amount of the alkyl ketene dimer surface sizing agent is as large as 0.025 g / m ² , so that smearing of the coating device occurs and the newspaper is continuously used. It was difficult to manufacture.

  Since Comparative Example 5 does not use a polyacrylamide adhesive as an adhesive, the water absorption time is as low as 25 seconds and the water resistance tension is as low as 3.1 seconds compared to Example 5 under the same conditions. Evaluation is getting worse.

  As described above, the newsprint of the present invention, that is, the newsprint coated with a predetermined amount of a predetermined surface treatment agent, satisfies the conditions that the water tension is 3.5 seconds or more and the water absorption time is 30 seconds or more. It can be confirmed that no contamination occurs. Then, it can be confirmed that no color misregistration occurs in the newsprint that satisfies such conditions.

  The newsprint for offset printing according to the present invention is a newsprint made by suppressing the use of an internal sizing agent, and is suitable for use on a cold set type offset printing press.

Claims (4)

Surface treatment agent is coated on both sides of the base paper so that the water tension is 3.5 seconds or more .
The surface treatment agent is
Includes an adhesive, an alkyl ketene dimer surface sizing agent, and a polymer surface sizing agent,
The coating amount of the alkyl ketene dimer surface sizing agent is 0.001 to 0.02 g / m ² per side ,
The ratio of the coating amount of the alkyl ketene dimer surface sizing agent and the polymer surface sizing agent is 1 to 4 to 4 to 1,
The adhesive is
Contains polyacrylamide adhesive and starch adhesive,
The newsprint for offset printing , wherein the mass ratio of the polyacrylamide adhesive in the adhesive is 5% by mass or more . The coating amount of the adhesive is
The newsprint for offset printing according to claim 1, wherein the newspaper is 0.3 g to 1.0 g / m < ² > per side . The newsprint for offset printing according to claim 1 or 2 , wherein a mass ratio of the polyacrylamide adhesive in the adhesive is 5 to 10% by mass . JAPAN TAPPI No. The newsprint for offset printing according to claim 1, 2 or 3 , wherein, in the test method according to 32-2, the time for absorbing 5 µl of dripped water is 30 seconds or more.

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